Building on engineering fundamentals in design, dynamics, measurement, and control, PI aims to develop an actively controlled photonic force microscopic (AC-PFM) system and to realize new capabilities for force probing and manipulation of active biomolecules in live cells. The fundamental building block of the proposed photonic force microscopic system is a three-dimensional (3D) probing system, in which a functionalized nano-bead is optically trapped around the minimum of the field potential to serve as the measurement probe, while the random thermal force tends to destabilize it. An innovative dual-measurement approach is proposed to enable feedback control. Novel nonlinear control schemes along with a 3-axis steering system are proposed to effectively change the field potential according to the absolute position of the measurement probe and enhance the stability of the optical trap, lower the required laser power, and thus reduce the temperature rise of the probe as well as that of the sample being probed. Theoretical and experimental investigations are proposed to estimate probe-sample interaction in noise, leading to the implementation of model-based estimators for 3D dynamic force sensing. The ability to sense the 3D probe-sample interaction force will enable individual molecules probing, force mapping, and force feedback control. Force feedback control will help maneuver the probe inside cells and achieve automatic scanning for intracellular visualization. If successfully developed, the proposed instrumentation will open new frontiers in research on active biomolecules. Public Health Relevance Statement: The proposed technological development will result in an actively controlled photonic force microscopic system that enables scientists to study biomolecules in live cells with new capabilities in terms of visualization and force probing. It will have significant impact on many aspects of biology, pharmacology, as well as medicine.